Of all the innumerable people afflicted with unpleasant body odor throughout history, it's hard to find a case more extreme than that of the Roman Emperor Galerius, who ruled from 305 to 311.

Galerius was a cruel monarch who persecuted early Christians, and some believed that divine retribution was visited upon him in the form of a mysterious disease. That affliction caused his flesh to rot and his intestines to become filled with worms, so that he exuded "such a pestiferous stink, that no man could abide him," as the religious historian John Foxe described it.

Eventually, the odorous (and odiferous) emperor reluctantly eased up on his persecutions, but it was too late. He was dead soon after issuing his Edict of Toleration [source: Encyclopedia Britannica]. Today, some think that Galerius suffered from a condition called Fournier's gangrene, made worse by his apparent diabetes. Both may have contributed to his extreme body odor, rather than poor personal hygiene.

Body odor generally starts with perspiration, particularly in the armpits and groin, which provides nourishment for bacteria that in turn give off unpleasant-smelling waste products. In most cases, regular bathing and use of a deodorant or antiperspirant can control the problem.

But sometimes, there are other causes for body odor— such as disease, diet and the use of certain medications — that have nothing to do with sweating. Here are 10 of them.